Could not zoom to an address when startup a map using Javascript Api

I have a very simple map with a basemap layer,a dynamic service layer, oeverview and TOC. when the map gets started up, I want to automatically zoom to an corresponding address area. I tried may events (map onLoad, layer onLoad, onUpdateEnd, and etc), it never zoom to the location the first time. But if I hit F5 on the page, it will work. Could someone tell me why or in which event, I should fire up the address locator to locate the address? Thanks!